The present invention relates to a brushless motor for driving magnetic disks such as high density hard disks.
In the conventional hard disk device, as shown in FIG. 4, a magnetic disk device 8 and a magnetic head assembly 9 are mounted securely on a chassis 22. The magnetic disk device 8 includes a plurality of information signal recording media or magnetic disks 12, each having a large data packaging density and mounted on a hub 4 which is rotated by a brushless motor. With this arrangement, recording and reproduction are carried out by a magnetic head slightly floating above each surface of each magnetic disk.
The magnetic head is attached to a swing arm 23 which in turn is connected to a rotating shaft 24, so that the magnetic head is rotated through an extremely small angle by a stepper motor or the like, so as to track a magnetic disk.
The floating height of a magnetic head is on the order of 0.2-0.3 .mu.m and, in order to ensure that this floating height is stably maintained, the magnetic-disk storage equipment is enclosed in an air-tight cover 25, so that the intrusion of the surrounding atmosphere and dust into the magnetic storage equipment is prevented and so that a predetermined desired degree of cleanliness can be maintained. However, as shown in FIGS. 5 and 6, which depict a motor designed, constructed and tested by the present inventor, a housing 1 of a motor is formed with through holes 1a and 1b through which magnetic sensors 5 and 6 and a coil 21 project, so that the surrounding air flows into the motor housing 1. As a result, a suitable means for maintaining the motor housing in an air-tight state is required. To this end, an air-tight sealing material such as epoxy resin 26 has been used to seal the magnetic-sensor-lead-wire holes 1a and 1b and the undersurface of a circuit board 19. However, there has arisen a problem that, once they are sealed in the manner described above, they cannot be disassembled in order to replace faulty circuit component parts.